I have had poor performance using 900 MHz omnis with SR9 cards. I have found that in almost every case, secorizing has made a difference, but the main help has been to switch to horizontal polarization. I have searched for 900 MHz horizontal sectors and have only found ones that cost close to $1000 each.
Some people have recommended trying the 9dbi PacWireless Yagi as an alternative to sectors. One question: How many would I need for good 360 degree coverage. A few people have said 2 back-to-back work decent, but from the little I’ve played around, I’d think at least 3 or 4 would be needed. Any ideas from anyone?
Also, can the SR9 cards be run through a 900 MHz splitter, such as the 2 or 3 way splitters from Hyperlink Tech? I was thinking that if 3 yagi’s would work, I could get by using 1 SR9 and hook it to 3 antennas. Does anyone have any experience with this?
We are using 900Mhz 4 slot Hpol sectors from Hills Antennas Australia. The
price is around $A600.00. They’re a large antenna physically, but effective.
Certainly the Yagis work well. We’ve used the 13db Yagi for Pt-Pt links
but have dropped customers of the side, and have thought of combining
three 9db Yagis to give a smaller Hpol alternative.
Another posibility is making up a 900Mhz cloverleaf. There is a Ham site
which has details for these on 900Mhz as well a circularly polarised version.
These are made of heavy copper wire, and could be fabricated cheaply in
volume..
Exact same thing I mite have to do, I am trying to use vertial pol with omni but picking up alot of noise etc etc, played arround with CPE and found on an H-pol I pick up alot less interference. does anyone have a sucessfull yagi sectoral setup running and how did you set it up 2 cards or splitter with one card? just curious please let me know thanks -Jordan
With the Pac Wireless 9dBi Yagi, I think it will take 3 for a v pol sector setup to have 100% coverage, although 2 would be pretty close according to some WISP’s I’ve spoken to. For h pol, 4 or 5. I’ve got to look at the beamwidths again.
For V pol on a yagi, you almost have a dipole, so you’d have decent side lobe coverage anyway, although not as strong of a signal as straight in front of the yagi. With h pol, you’re side lobes will be coming from the top of the antenna, which are almost nonexistent.
All I really need is 75 percent there is other areas that I know I dont need coverage to, I was hoping only 2 3 yaig’s H-pol, I need H-pol I think because of the interference.
I wasn’t planning 100% coverage myself. 900MHz usefulness is limited, so I was only planning on 2 yagis myself, pointing in the general direction of customers behind trees.
100% coverage was for the purpose of the discussion.
Gotcha, How bad of it would be of me i used a splitter and 1 card? My plan is to by a ubiquiti cavity filter, for my vertial omni setup, if that dosen’t work, Pull the omni get a splitter and 2 yagi omni’s and also connect the ubiquiti cavity filter. I get alot less noise (testing with CPE) with H-pol. I would need at least 75 percent coverage though. Mite need 3 yagi’s… I did look at the projections map and it looks like 2 9 dbi yagis would get almost 75 percent.. That’s what i’m faced with what would you suggest? -Jordan
Tryed the 2 9dbi Yagi trick, does not work, Good noise floor, Horrible distance, If your close to it you can pull some incredible data over 900mhz though I got a bandwidth test of one way up to 21 Mbps. Pretty impressive, then again it was only 500 feet away. Distance was horrible though… Almost had to be LOS to get an acceptible signal level, I am presuming this is do the the pattern of the signal from the Yagi, Just did not work Like My other Omni antenna did, So I mite have to try a omni with filter in this location or rob a bank to get the sectoral H-pol Sectors. Jordan B
I would advise getting the good hoz sector or omni despite the cost. The antennas are a very important part of the link. At 900mhz a clean pattern is very important, and you need the good antennas to get that. This reduces noise and increases gain. If you use a bad antenna at the AP you will end up compensating with every customer, and that’s a lot more work and expense than doing it right at the tower.
Superpass makes some nice horizontal 900mHz sectors for 300-400USD, price depending on pattern width and depth. We’ve got a lot of them deployed and have been very happy. H/V separation is good. The mounting arrangement is not as nice as we’d like (no scissors) but it’s fairly easy to work around this problem, if you need tilt.
It’s worth a step up from Superpass for 900mhz. Pacwireless or MTI will provide a superior signal of 3-4 higher DB than superpass for a given advertised gain and pattern. Otherwise, superpass isn’t a bad 900mhz antenna.
You may be better of with a good filter. The filtering on the SR9 is not great, in fact I believe that the receive channel is a full 20mhz and only the TX is 5/10.
The cards seem very susceptible to “noise” from collocated equipment and from other sources.
We had a site (XR9 which are a bit better) in a very noisy area one with a pol tower just a few hundred meters away. We are running with nstreme and a 1500 byte packet.
The Hpol sector we used help a lot but we found that the majority of our problems (stuff just did not work) were self induced by our other sector. A channel filter was used and made our 900 usable again.
If you have collocated gear this is likely at least part of your problem. Do a BW test to some of your marginal clients. If your receive (upload) is crap but you get some down load turn off all your other near by gear and see if your receive improves… it will if you are collocated. This issue is often a sleeper because when you start the traffic is light… as more clients are added things get progressively worse because more packets get stomped on. When traffic was light things got through.
At our site the improvements were nothing short of fantastic. We went from something that we wanted to rip out to some happy customers.